Day: October 31, 2011

Who hasn’t thought about turning a 1950s slide projector into a digital projector? [Matt] did, but unlike most of us, he actually did it.

[Matt]’s friend [Angus] found an old, single-slide, sans-carousel slide projector in the trash. It’s a wonderful piece of ancient technology with a fabric insulated power cord and bakelite lamp socket. This projector was upcycled to the 21st century by adding a 10 Watt LED and a Nokia 1200 LCD.

For the electronics, [Matt] used an ATmega88 microcontroller. There’s an infrared receiver so the remote from an in-car CD player can be used to advance the slides and turn the projector on and off. The LCD is controlled by a bit of bit-banging from the Mega88, using hard-coded images of Che Guevara, Hendrix, Space Invaders and some old-school Macintosh/Lisa icons. Unlike the screen printed t-shirts at American Apparel, Che is the only authentic image in this project; this projector might have been made after Guevara came to prominence.

With a 10 Watt LED, it’s not the brightest projector on the planet and the picture is a little washed out in a bright room. With dim lighting, it’s a very good project even if the images are static.

The Halloween parties this weekend are over, but that doesn’t mean there’s not time for a few more to finish a build before children start knocking on doors tonight. [formori] at Lakehead University wanted to do something spectacular for a pumpkin carving contest, so he and a few other EE students came up with a tiki-o’-lantern with music.

The guys at Lakehead figured a color organ flashing LEDs in the eyes and mouth of the tiki would be a very good and easy project. The circuit they used is a simple Op-amp setup like one we’ve seen earlier. The entire pumpkin is powered by a 9 V battery and the music is played with an iPod. There are two colors of LEDs – high frequencies flash a blue LED in the eyes and low frequencies flash a red LED in the mouth.

Aside from the added A/V stuff, [formori]’s pumpkin is one of the best we’ve seen on Hack a Day this year. Check out the Youtube of 1st place winner of the Lakehead pumpkin carving contest after the break.

Never get between a man and his salami. [Mike] needed a way to control temperature, humidity and airflow with his meat curing setup. Of course he could modify a refrigerator and humidifier to be controlled separately, but [Mike] decided the best course of action would be to control line voltage with an Arduino.

[Mike] started his build with a four socket wall housing he picked up at Home Depot for a few dollars. After wiring up each outlet so it can be controlled independently, he set out designing a four port relay board. This was a pretty simple build – four 10 Amp relays and a few terminal blocks. The PCB was designed in Eagle as a single-side board for ease of manufacturing.

The relay board is meant to fit inside the blue box along with the four sockets, so a few holes were drilled for the power and control wires. The entire assemblage was put together and tested out. [Mike] posted a video of his controllable outlet flashing a light bulb at 10 Hz. Check out that light switch rave after the break.